1969 Chris Craft Roamer 46 Refit: Fuel Supply Manifold

With the on-engine supply and return fuel hoses installed and fuel gauge at the helm working, next I finished assembling the fuel supply manifold.

I bought all of the stainless fittings, connectors, and valves I thought I’d need more than five years ago. They were sitting in a box in my garage taking up space, so it was nice to finally put them all together.

One challenge I encountered was that all of the fittings, connectors, and valves use 1/2″ NPT threads. The manifold is basically a loop with valves, inlets, and outlets, but it’s impossible to thread fittings together to make a loop. I resolved that problem by making two halves of the manifold, then used Swagelok 1/2″ NPT to tube adapters to slide them together and complete the loop.

Swagelok tube fittings let me assemble the two halves of the manifold

I’ll attach the manifold to some 1/2″ thick PVC backing board I found in my garage. So I made some stainless straps to hold it all together. I bent the stainless around a handy 3/4″ pipe first to put a curve in it.

Bench vise brake makes nice 90° bends in stainless strap

Next I drilled screw holes in each strap

Gasoila seals all the joints and prevents stainless galling

I used 1/2″ full port stainless valves in the manifold to reduce restriction. The up-side of a manifold like this that allows me to feed each engine on separate tanks or all from any of the three tanks onboard. The downside of it is the number of 90° fittings, each one of which adds friction to the system equivalent to ~7′ of 1/2″ straight hose or tubing. In normal service, with each tank fed by its own respective tank (stbd-stbd, port-port), just going through the manifold adds 14-feet worth of straight pipe friction (~.1″ HG/ft).

Nice!

This explains what each port will connect to

The best place for the manifold will be under the big Kidde CO2 tank

Test fitting the SMX fuel filter

Several years ago I bought two SMX filter heads and Fleetguard 19513 “mud filters” from Tony Athens’ Seaboard Marine in anticipation of this day. Good thing I had them on hand! It quickly became obvious that I’d need to mount the filter heads ~1.5 inches away from the plane of the manifold so the valve handles would clear the filter heads.

Uh…Houston…we have another problem

With the manifold backing board clamped to the best spot under the CO2 tank, there’s not enough clearance to remove and install the fuel filters. Good thing I had lots of that 1/2″ PVC backing board laying around…

Trace the SMX fuel filter head base on the 1/2″ PVC

ShopSmith bandsaw makes quick work of the PVC

Same ShopSmith machine also has a 12″ disk sander that comes in very handy

I rounded off the sharp edges to match the SMX filter head base

Then I screwed three of the 1/2″ PVC pieces together to make 1-1/2″ filter head spacers

I also made PVC spacers that will allow me to locate the manifold outward and higher up on the Kidde CO2 tank support frame.

These spacers on the back of the manifold backing board will give me the clearance I need

1.5″ inboard and 6″ higher…final test fit looks good!

Tefgel protects the aluminum frame from the stainless bolts that attach to the PVC backer board

I use a touch of Tefgel to lubricate threads and isolate the aluminum AN fittings from the stainless ones

Looks good!

Starboard engine diesel supply hose is attached to the supply manifold!

It’s not so consequential, connecting the on-engine fuel supply hose to the fuel distribution manifold. But there are only so many connections between the tank pickups and the engines. Each one that I complete gets me substantially closer to being able to fire these Cummins 6CTAs up!

Next up in our 1969 Chris Craft Roamer 46 Refit: Engine Room Ventilation Fan